JP2000199571A - Sheet ring of eccentric butterfly valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a seal effect from decreasing by making small the thickness of a movable part of a sheet ring, and deforming the movable part into a spiral shape so as to bite a valve element when fluid pressure is additionally given to a pocket-like recess. SOLUTION: A sheet ring 10 is fitted and retained by a retainer to an inner circumferential stepped part 15 of a body 11, a base part 10a of the ring 10 is held between the body 11 and the retainer 12, and a protrusion 16 formed at the retainer 12 is engaged and inserted, thereby preventing slipping out in the inner diameter direction and leakage of fluid to a secondary side through the rear side of the ring 10. Such a sheat ring 10 has a movable part 10b extending out toward the outer circumferential surface of a valve element 13 from the base part l0a, and a semicircular pocket-like recess 17 is formed at a primary side of the moving part 10b. When fluid pressure is added to the recess 17, the movable part 10b is deformed spirally and allowing it to bite the element 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat ring mounted on a main body of an eccentric butterfly valve, and more particularly to a seat ring suitable for controlling a low-temperature fluid.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a pocket-shaped concave portion (2) for receiving a fluid pressure (A) on a primary side when a valve is closed is formed in a seat ring (1), and is added in the pocket-shaped concave portion. The seat ring (1) is deformed in the direction of the arrow (B) by the applied pressure to achieve sealing. The structure that achieves sealing with the pressure applied to such a seat ring is:
Particularly, it is called a pressure seal structure, and is disclosed, for example, in Japanese Utility Model Laid-Open No. 60-2061. At a temperature higher than room temperature, such a seat ring with a pressure seal structure ensures sufficient flexibility of the seat ring, so that the pressure seal effect is exhibited, but the flexibility of the seat ring decreases at low temperatures. However, there is a problem that the pressure seal effect cannot be obtained. For example, in the case of polytetrafluoroethylene, if the elasticity at room temperature is 10, it is known that the elasticity decreases to about 2 at −20 ° C. According to an experiment, it has been confirmed that the sealing performance of the sealing structure of FIG. Further, in this structure, since the deformation point (P) of the seat ring (1) when pressed is close to the sealing point, a large force is required to apply rotation in the direction of arrow B, and the deformation is small at low temperatures. Therefore, it is difficult to obtain a sealing effect.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a structure in which a seat ring does not lose its flexibility even at a low temperature, thereby preventing the sealing effect from being reduced.

[0004]

Means adopted by the present invention to solve the above-mentioned problem is that the retainer is mounted and fixed on the inner peripheral surface of a cylindrical fluid passage in the main body, and is eccentrically located in the fluid passage. An eccentric butterfly valve seat ring having a pocket-shaped recess receiving a fluid pressure when the valve is closed. A gap is formed between the movable portion extending from the base portion held toward the valve body and the main body, the thickness of the movable portion is reduced, and when the fluid pressure is applied to the pocket-shaped recess, the movable portion is removed. It is characterized in that it is deformed into a swirl shape and bites into the valve body.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below. Referring to FIGS. 1 to 3, (10)
Is a seat ring, which is mounted and fixed to the inner peripheral surface of a cylindrical fluid passage in the main body (11) by a retainer (12). Body (11)
A disc-shaped valve element (13) is eccentric in the fluid passage of the valve stem (14).
, So that it is rotatably supported, and is freely movable toward and away from the seat ring (10). Referring to FIG. 2, the seat ring (10) is
It is mounted and retained on the inner peripheral step (15) of (1) by the retainer (12). The base (10a) of the sealing (10) is sandwiched between the main body (11) and the retainer (12), and the projection (16) formed on the retainer (12) engages with the base (10a) in the inner diameter direction. And the fluid is prevented from leaking to the secondary side through the back side (outer periphery) of the seat ring (10). The seat ring (10) has a base (10a) held between the main body (11) and the retainer (12).
Movable part (10b) extending toward the outer peripheral surface of valve body (13) from
A semicircular pocket-shaped recess (17) is formed on the primary side of the movable part (10b), and the tip of the movable part (10b) is a valve body.
(13) can be pressed against the outer peripheral surface.

According to the present invention, in the seat ring of the butterfly valve, a gap (C) is formed between the seat ring and the main body (11) so that the seat ring does not lose its flexibility even at a low temperature. Is characterized in that its thickness (t) is reduced. Furthermore, the seal compression part (b) that comes into contact with the valve body (13)
, The opening and closing torque of the valve body is reduced. Since the opening / closing torque of the valve body is affected by the amount of compression at the time of sealing, it is possible to reduce the opening / closing torque by reducing the compression area. The size of the gap (C) between the seat ring (10) and the main body (11) is not particularly limited, but is at least 0.3 mm, particularly preferably at least 0.5 mm. The thickness (t) of the movable part (10b) is preferably about 3 mm in order to secure a required compressive force. However, since the size of the seat ring (10) is different depending on the valve diameter, the above-mentioned numerical value indicates a guideline for a polytetrafluoroethylene seat ring having a diameter of 200A, and the size of the diameter is small. And it is necessary to change it appropriately according to the material. Although the material of the seat ring (10) is not particularly limited, as the polytetrafluoroethylene material, TFE or RPTFE is preferable.
In the case of PTFE, glass fiber 30% or less, carbon fiber 1
Those containing 0% or less and 35% or less of carbon graphite are preferred. The rubber material may have a hardness of 60 to 80,
Preferably, it is 75, and the tensile strength is 200 to 800 kgf / c.
High-strength rubber of m ² , preferably 600 kgf / cm ² or more is preferred.

Referring to FIG. 3, when the valve is closed, a pocket-shaped concave portion is formed.
When the fluid pressure (A) is added to (17), the movable part (10b)
Since it turns around the deformation point (P) as shown by the arrow (D) and deforms so as to bite into the valve body, the deforming force is reduced and the sealing effect can be easily obtained.

[0008]

According to the present invention, the seat ring can maintain sufficient flexibility even at a low temperature, and a reduction in the sealing effect can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a butterfly valve to which the present invention is applied.

FIG. 2 is an enlarged sectional view of FIG. 1X part;

FIG. 3 is a diagram showing an operation state of the same part.

FIG. 4 is an enlarged sectional view of a part of a conventional seat ring.

[Description of Signs] (10) Seat ring (10a) Base (10b) Movable part (11) Main body (12) Retainer (13) Valve (14) Valve stem (15) Step (16) Projection (17) Pocket -Shaped recess A Fluid pressure C Gap D Arrow t Thickness b Compressed part P Deformation point

Claims (1)

[Claims] 1. A seat ring which is attached and fixed to an inner peripheral surface of a cylindrical fluid passage in a main body by a retainer, and is capable of coming into contact with and separating from a disk-shaped valve body which is eccentrically supported in the fluid passage. In a seat ring of an eccentric butterfly valve having a pocket-shaped concave portion that receives fluid pressure when the valve is closed, between a movable portion extending from a base portion held between the main body and the retainer toward the valve body and the main body. A gap is formed in the movable portion to reduce the thickness of the movable portion, and when fluid pressure is applied to the pocket-shaped concave portion, the movable portion is deformed in a swirling shape so as to bite into the valve body. Eccentric butterfly valve seat ring.